The invention relates generally to apparatus for use in wheel lift type towing systems. More specifically, the invention concerns a pop-up wheel-engaging dolly for elevating a coaxial pair of towed vehicle wheels.
Known dollys for raising a towed vehicle by a pair of coaxial wheels typically utilize a pair of dolly bases equipped with a dolly wheel at opposing ends which are placed at the outside lateral surface of the two tires to be lifted. Cross arm assemblies are then connected between the two dolly base members and means are provided at each wheel for raising the associated dolly wheel spindle to a towed position. In mechanical, manually actuatable arrangements, some prior systems typically use a ratchet gear mechanism for lifting and then a separate manually engagable master lock for holding the elevated dolly wheel spindle in the actuated position. Another type of manually actuatable system features simply a master lock mechanism without use of the ratchet type gear.
Also known in the art are hydraulically actuated self-loading dollys featuring relatively expensive and complicated hydraulic systems for use in raising and lowering the dolly wheel spindles.
Thus the hydraulic systems of the prior art are complicated, relatively expensive and require increased maintenance. The manually operated systems of the prior art require manual final locking in the actuated position.
There is a need for a relatively non-complex and economical pop-up dolly arrangement having wheel actuators providing for automatic dolly wheel spindle locking and release functions for respectively raising and lowering corners of the dolly cradling the wheels of a towed vehicle.